Currently I have a th350 in my truck and it does ok when towing, just need more first gear and/or lower rear end gears (which are getting swapped to 3.73 or 4.10 depending on the tranny i choose). I already have a 700r4 that just needs rebuilding and I am going to go with the full B&M transkit for it. I will be towing probably 7000 lbs. max only a few times a year with my truck (the th350 handled it fine). Current plans and somewhat near future (year or so), I will be adding heads and a super charger to my 350 and will be putting out somewhere between 450-480 hp. Will the 700r4 be good enough with the B&M kit or should I go ahead and get a th400 for $700 from summit and deal with out the overdrive and worse mileage on my trips when I don't tow a trailer. I will tow the 700r4 in drive not overdrive. Any opinions or suggestions appreciated. Any experiences with 700r4's towing? Thanks.
Greg

I tried a built 700R4 and it did make it that long. As soon as you drop it into OD towing (on flat land) the tranny temp would just creep up. It did not help with mileage that much at all.

I would find a boneyard TH400, take it to a local slushbox expert, and go from there. You don't want to tow 85 mph anyhow.

I'd go with the 400. have seen way too many 700's smoked. yes I have even seen them professionally built ($2k+) and still get toasted by a 350 horse smallblock. my advise is get a 400. have you priced having a 700 rebuilt anyways? if you go with the 700$ 400 from summit you'll be getting awya cheaper, put it that way!

-Scott

thanks. that's what i figured. the transkit for the 700 is about $350 or so, then having it rebuilt from a buddy is about $350 or so as well, so I might as well go with a new th400, and I know the 400 will handle just about anything I throw at it.
Greg

thanks! makes my decision a lot easier.....mega strong th400 for $700 ready to go...or $7-800 for a rebuild that will be toasted after a few towing trips....
greg

Personally, I didn't like the TH700 for towing. 2nd is too much of a drop from 3rd & the 1-2 gap is even bigger. And forget about OD if you want your tranny to live - I didn't even use it running empty unless I was going 70+ on the Interstate. TH400 isn't geared any lower than your TH350, but is somewhat tougher. But, personally I'd do a quality rebuild on your TH350 & be done with it.

TEX

Originally posted by KMAN
You don't want to tow 85 mph anyhow.

Don't tow much in Texas, do ya? :D Yes, there are crazy folks who really do tow like that down here. :eek:

Greg -- go pick up a copy of Ron Sessions book the the TH400... and just get to work rebuilding it yourself. Great learning experience (easier than a manual gearbox)... don't worry after the SECOND rebuild you'll be pretty familiar with it. :D

Tom :usa:

thanks for the help!
btw, roundrocktom, where is cedar park?
greg

a 700 is only good for 450 flbs of tourqu anyway my old man is on no 5 700 :rolleyes: :( Go with the 400 you wont look back but if you really want the OD get an 4l80e IIRC but that swap is major $$$

it has the stranght of a 400 but with the OD of a 700

I ditched my Art Carr Turbo 350 the first time I floored my freshend up built to the hilt supercharged 350 when it grenaded shifting into 2nd gear the first time I got on it hard. It had lived behind a stock but supercharged 350 for 60000 miles but still...
I've run a 700R4 since AA built the adapter to mate them to the 203 fulltime case many moons ago. Mine was one of the first adapters to go out AA's door. Anyway the 700R4 has always had all the best parts thrown in it by builders that knew there stuff and still I never got more than 13000 miles out of them behind a built supercharged 350. I had everything from progressively softer shifts, no 2nd gear, ratcheting when extreme sidehilling tilting to the left, no full throttle 1st gear kick down, converter clutch soft engagement problem and more. After cracking the case in half I ditched it as that was the only time in left me stranded! In went a Turbo 400 which I have never had a problem in various other cars and trucks. The 700R4 did not seem to help my mileage much because of a big cam and lower rpm don't go well together--no problem with power just the gas gets pushed out both open valves by the supercharger on overlap! But the 1000 rpm drop is sure nice on the ears. Anyway go 400 with a Gear Vendors overdrive or 4L80 in you must have overdrive. You will be happier once you build your motor

Jason :)

the gear vendors claims are nice...but for $2400 or so, I think I'll live without the OD for now, however, it would be nice to split the gears when towing. I'd still tow in 1:1 prob, but still, would be nice to have. would anyone like to donate $2400 to the gear vendor experimental fund? Thanks, please send to...
Greg

Originally posted by bignissan
thanks for the help!
btw, roundrocktom, where is cedar park?
greg

Right next to Round Rock, TX! :p

Uh... about 10 miles NorthWest of Austin. Round Rock is right on I35. I actually live in the between the two locations... technically county, but Cedar Park mailing address.

Tom :usa:

that's not too far from houston...bout 3 1/2 hours or so...
greg